Mobile device location identification may be accomplished through multilateration techniques, e.g., Global Positioning System (GPS). GPS is a satellite-based navigation system made up of a network of satellites placed in orbit. GPS satellites circle the Earth and continually transmit messages to Earth that include the time the message was transmitted and the satellite position at the time of the message transmission. A GPS receiver uses the messages it receives from multiple satellites to determine the transit time of each message to calculate the location of the GPS receiver. Multilateration is a navigation technique based on the measurement of the difference in distance to two or more stations at known locations that broadcast signals at known times. For example, with a mobile phone, location identification may be accomplished through the use of multilateration of radio signals between several radio towers of the network and the phone.
A geographic information system (GIS) is a system designed to capture, store, manipulate, analyze, manage, and present all types of geographical data. In general, GIS describes any information system that integrates, stores, edits, analyzes, shares, and displays geographic information. GIS applications can allow users to create interactive queries, analyze spatial information, edit data in maps, and present the results of these operations. GIS data represents physical objects (such as roads, land use, elevation, trees, waterways, etc.) and this data may be varied based on the design of the GIS and its intended use.